Stylus for sound-reproducing machines.



STYLUS FOR SOUND REPRODUCING MACHINES. APPLICATION man MAR-19.1915

1,237,230. Patented Aug. 14, 1917.

Inventor: Willis R.Whitne UN TED STATES PATENT OFFICE.

WILLIS R. WHITNEY, OF-SCHENECTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

STYLUS FOR SOUND-REPRODUCING MACHINES.

Specification of Letters Patent. i Patented Aug. 14, 1917.

Application filed March 19, 1915. Serial No. 15,541.

To all whom it may concern:

Be it known that I, WILLIS R. WHITNEY,

a citizen of the United States, residing at Schenectady, in the countyof Schenectady,

State of New York, have invented certain new and useful Improvements inStyli for ticularly to styli or needles having a tip of tungsten ortungstenic material, such as are described in U: S. Letters Patent No.

The object of my invention is to provide an improved method of and meansfor securing the tip to the bodyportion of such needles'whereby they maybe produced eco nomically and will be efficient in their operation aswell as durable.

- The point of such a needle should preferably. have a diameterapproximately equal to the width of the groove in the sound record withwhich it is to be used or about .006 of an inch.

I have found that such needles may be made to advantage by securing thetungsten point directly to the end of the body portion by means of abody of metal having a lowermelting point than either the point or thebody. portion.

In carrying my. invention. into effect I have found that copper or analloy thereof is most suitable for joining the tungsten point to thebody portion. This is because of the fact that under non-oxidizingconditions molten copper readily wets tungsten and also wets the steelwhich preferably forms the body portion of the needle. The copperused'is preferably first treated with a small quantity of an oXidizab-leboron materlal as described in Weintraub Patent #.1,023,604.

' In joining the point to the body portion I have found that there is atendency for the copper to run down over the sides of the body portion.In order to secure a uniform prod- .uct it is necessary to use for eachneedle a predetermined amount of the metal which forms the union betweenthe point and the body portion which amount should be ]ust suflicient toproperly join the two parts. If

in some cases a part of this metal runs over the side of the podyportion the junction between the point and the body portion will bedefective. I have found that this difficulty may be overcome by treatingthe sides of the body portion in such a way that they will not be wet bythe molten copper. This has the additional advantage of causing thecopper when molten to form a rounded globule on the end of the bodyportion and if the point is placed in the center of this globule thedesired form of needle may be.

obtained by the joining operation without any further mechanicaltreatment.

My invention with further objects and ad vantages will best beunderstood by referonce to the following description taken in connectionwith the accompanying drawing in which Figure 1 represents the sound boxof a sound reproducing machine provided with a stylus-"constructedaccording to my invention, in engagementwith a sound rec- 0rd tablet;Fig. 2 shows a convenient form of support for holding the needles whilethe points are being attached to the body por-- tions; Fig. 3 shows theparts of a needle before they are joined together; Fig. 4: shows theneedle after the parts have been joined together; and Fig. 5 is agreatly enlarged view of the point end of a completed needle.

The sound box 1 of the sound reproducing machine shown in Fig. 1 isprovided with one of my improved styli 2 secured to the transmission arm3 by means of a suitable holding device 4' and the point of which restson a sound record tablet 5.- The sound box transmission arm and bolderhowe er form no part of my present invention but are shown merely toillustrate one way in which my improved stylus may be used.- The bodyportion 6 of the stylus illustrated in Figs. 3, 4 and 5 is preferably ofsteel. The metal for joining the point-to the body portion may beprepared in the form of a small disk 7 of the same diameterneedles' asshown in Fig. 3 may be assembled for the joining operation in a supportof the type illustrated in Fig. 2. This consists of a base portion 9having slotted ends adapted to receive an upright perforated bodyportion 10. 1 The perforations in this body ortion of the holder aremade of slig tly larger diameter than the body portions of the needles.When the portions 6 and 7 of the needles are assembled in the bodyportion 10 of the holder they may convenientl be substantially flushwith the top thereo A perforated cover 11 which may be held in itsproper position by pins 12 at each end is then placed over the bodyportion 10. The points 8 are then inserted in the perforations in thecover which register with the -perforations in the body portion 10. Whenthe parts have been thus assembled the support is placed in a hydrogenfurnace heated to a temperature at which the copper disks 7 will melt.As soon as these disks melt the points 8 drop down into the molten metaland may touch the ends of the body portions 6. The sup orting memberwith the needles therein ist en withdrawn from the heated section of thefurnace and allowed to cool while still in the hydrogen atmosphere andwhen cool it will found that the points are securely attached to thebody portions.

The needlesmay then be removed from the support. If the operation hasbeen properly carried out the needlm should have the apearance indicatedin Fig. 4 that is, the

joining metal should have substantially the form of a hemisphere withthe point protruding from the center thereof. Since the tungsten is wetby the copper the. surface of the copper around the point will beslightly raised as indicated more clearly in Fig. 5.

In order that the needles shall have this form I have found it necessaryto treat the cylindrical surface of the body portion 6 in Such a waythat it will not be wet by the molten copper. otherwise the copper willrun down over the body portion, and cause the needles to stick to thesupporting member. When this happens too there may not be enough metalleft to properly join the point to the body and the metal that is leftinstead of having a rounded surface as desired, will have a fiatsurface. I have found that the desired'efi'ect may -be secured byforming on the surface of the body. portion 6 a coating of aninoxidizable alloy of aluminum and lI'Ol'l. This may be done by heat-.ing the body portion in contact with powdered aluminum undernon-oxidizing conditions'as described in an application filed by TychoVan Aler October 4, 1911, Serial No. 652,756. A comparatively thincoating is suflicient for my purpose and the necessary thickness may besecured by heating about half an hour in the manner described in theThis will give. a clean end surface to which the oint may easily besecured.

The points 8 may be cut from tungsten wire of the desired size which hasfirst been carefully straightened and cleaned so that the copper willadhere to it readily. They may be cut to such a length that when theoining operation is completed they will protrude the desired amount fromtie joinin metal. Since this distance is very small an an variationtherein is not desirable consi erable accuracy in the construction ofthe supporting'member and in the assembly of the needles therein may berequired to secure the proper length of points in this way. On thisaccount it may be desirable to cut them at first longer than necessaryand trim them all to a uniform length after the joining operation hasbeen completed. As a final step in preparing the needles for use on asound reproducing machine it is desirable to subject them to a bufiingprocess to remove an sharp corners and give the points the smoot roundedappearance shown in Fig. 5.

\Vhile I have described but a single embodiment of my invention it willbe apparcntthat man modifications ma be made in the form 0 the arts usedand in the final form of the comp eted needles without departing fromthe scope of the appended claims. It will also be apparent that themethod which I employ for joining the tungsten points to the bodyportions may also be useful for other purposes than the manufacture ofneedles for sound reproducin machines.

TVhat I claim as new and desire to secure by Letters Patent of theUnited States, is

1. The method of joining a tungsten point for a stylus for soundreproducing machines to a steel body portion which consists in firstforming on t e side of the steel body a thin film of an alloy which isnot wet by molten copper and then melting a disk of copper on the end ofsaid body ortion under nonoxidizing conditions wit the tungsten point incontact with the copper disk.

2. The method of joining a body of tun sten to the end of an elongatedsteel y which consists in first forming on the side of the steel body athin film of an alloy .Which is not wet by molten cop er and thenmelting a bod of copper on t e end of said steel body un ernon-oxidizing conditions with the tungsten body in contact with thecopper.

to a body portion of a different metal by means of a joining metalhaving a lower melting point than the tungsten point or the bodyportion, which consists in first forming on the side of the body portiona coat ing of a material which is not wet by the joining metal when thelatter is molten, and

then melting a body of the joining metal on the end of the body portionwith the tungsten point in contact with the oining metal. 10

In witness whereof, I have hereunto set my hand this 18th day of March,1915.

WILLIS R. WHITNEY.

